Dec 14 () - Overview -- We expect U.S. aggregates producer Vulcan Materials Co.'s 2012 full-year EBITDA to fall short of our previous estimates despite improved operating results in the last four quarters, with leverage higher than our previous estimate of 6x. -- Vulcan seeks $500 million in after-tax proceeds from planned asset sales. While not yet determined, some or all of these proceeds may be utilized for additional debt reduction. -- We are affirming our ratings on Vul